1. Field of the Invention
The present invention relates to a main mouth of a brick molding machine capable of press-molding a product such as a brick, a sidewalk brick, a tile, etc. using cay or porcelain clay.
2. Description of the Background Art
Generally, a product such as a stacking brick, a sidewalk brick, etc. has been fabricated in a fabrication process in which a certain material such as clay or the like press-molded using a brick molding machine is cut into a certain size and processed in a firing furnace. The conventional brick molding machine includes a main mouth installed between a pressing unit for pushing a certain material with a strong pressure and a mold.
In addition, the main mouth is fabricated using a special steel having a certain strength that has a lower wearing degree with respect to a friction with clay or porcelain clay, for example, a Hi-Cr special steel.
FIGS. 9 and 10 are views illustrating a structure of a conventional main mouth.
As shown in FIG. 9, an inlet part 310 of a main mouth 300 is thread-engaged with a mounting flange 200 mounted at a front end of a pressing unit 100 of a brick molding machine using a bolt. A mold 400 is engaged at an outlet part 320 of the main mouth. A liner 410 made of special steel is engaged at an inner surface of the mold 400.
The inlet part 310 of the main mouth 300 has a circular inner surface at its cross section like a circular inner surface of the pressing unit 100 of a brick molding machine. The inner diameter of the same is getting smaller and smaller in the direction of the outlet part 320. Namely, an inner surface of the main mouth 300 has an inner diameter that is getting smaller and smaller in the direction of the outlet part 320 at the inlet part 310.
The material discharged through the pressing unit 100 of the brick molding machine has a certain friction resistance and compression force at its outer surfaces contacting with an inner surface that has a certain inner diameter getting smaller and smaller at the time when the material is moved into the inlet part 310 of the main mouth 300, so that its moving speed gets smaller. However, the moving speed at the center portions of the material gets higher and higher as compared at the outer sides of the same. The front sides of a pressing material press-molded by the mold 400 after passing through the outlet part 320 of the main mouth 300 are pressed with a protrusion as shown in FIG. 9. The above phenomenon occurs due to a certain stress by a transfer pressure at the center portion of the pressing material 500. The stress being applied to the center portion of the pressing material 500 is generated at the time when the pressing material 500 is cut into a certain size and is inputted into a firing furnace, so that a product 500 has a certain problem that a bent portion is formed as shown by an imaginary line of FIG. 9.
In order to prevent the above problems of the product 500, as shown in FIG. 10, a resistance protrusion 330 protruded in a streamline shape at an inner surface of the main mouth 300 is integrally formed at both opposite upper and lower sides (left and right sides) or is integrally formed at all sides of the same for thereby preventing the stress at the center of the pressing material 500, so that it is possible to fabricate a good quality of product that is not bent after a firing process.
However, the above conventional art has the following problems.
Since the resistance protrusion 330 is formed at an inner surface of the main mouth 300, a lot of friction occurs with materials, so that the resistance protrusion 330 is fast worn out. When the resistance protrusion 330 is worn out a lot, it is impossible to exchange only the resistance protrusion 330. Namely, it is needed to exchange the entire structure of the main mouth 300. Therefore, the life span of the main mouth is significantly decreased. In addition, since the main mouth 300 is made of special steel, the cost is too expensive. A lot of cost is needed in order to exchange the main mouth for increasing economical load. The above economical load directly affects the fabrication unit cost of the product resulting in a fabrication price of the product.
In the conventional art, the pressing operation of material moving into the mold 400 is enhanced using a certain unit capable of supplying oil (light oil, etc.) through an oil block 600 in which a plurality of oil inlet holes 610 are formed between the outlet part 320 of the main mouth 300 and the mold 500 in order to enhance the fluidity of the material when a certain material having high viscosity is adapted to fabricate the product. However, the above oil block 600 is formed in a single structure. When the oil block is made of special steel, the fabrication cost is too high. When the oil bock 600 is made of a metallic material, not special steel, the abrasion ratio is increased, so that the life span of the oil block is decreased. In addition, since oil is supplied only through the oil inlet holes 610 formed at multiple portions (mainly, four portions) of the oil block 600, a lot of oil should be supplied to each oil inlet hole 610 in order to uniformly apply oil onto an outer surface of the pressing material 500. In this case, oil consumption amount is increased. When a lot of oil is on an outer surface of the pressing material 500, the drying time of the product 510 is extended, so that energy consumption is increased, and the productivity by unit time is decreased.